NEW YORK (CNNMoney.com) — In a sign that more foreclosures could be on the horizon, 23% of people with mortgages owe more than their home is worth, according to a report released Tuesday.

Almost 10.7 million U.S. mortgages were “underwater” as of September, said research firm First American CoreLogic.

Another 2.3 million homeowners are within 5% of negative territory, the report said. The two figures combined comprise almost 28% of all residential properties with mortgages.

Negative equity, also called an “underwater” or “upside down” mortgage, has become more common as home values plummet. The report is closely watched because borrowers who are underwater are more likely to be foreclosed.

Would you walk away from your house?
Foreclosures have been rampant for some time, but lately the tide of decay had seemed to be slowing — so Tuesday’s report could dent optimism for the housing market over the next few months.

On the other hand, the trend that turned so many mortgages upside-down — falling home prices — has reversed the past six months. The S&P/Case-Shiller HomePrice Index has reported two consecutive quarters of increasing prices.

If home prices continue to go up or, at least stabilize, fewer mortgage borrowers will find themselves underwater in the coming months.

CoreLogic changed its methodology for the third quarter — now it accounts for payments that reduce principal, and it no longer assumes home equity credit lines have been maxed out. Using the old method, 33.8% of borrowers would have been underwater in the third quarter compared with 32.2% in the previous quarter, according to a CoreLogic spokeswoman.

State totals: The majority of underwater mortgages are heavily concentrated in five states that have particularly suffered from the housing bust: Nevada, at 65%; Arizona, at 48%; Florida, at 45%; Michigan, at 37%; and California, at 35%.

These five states have been especially beleaguered because of a high rate of prime loans that went bad. Many of those loans were option-adjustable rate mortgages, in which borrowers could choose to make minimum payments that were so low they did not even offset the interest being accumulated.

When that accumulated debt reaches a certain point — usually 10% to 25% more than the original principal — the option-ARMs loans are recast into fixed-rate mortgages. When that happens, many borrowers cannot afford the new payments.

Thanksgiving is one of the BIG food holidays for Americans (and Canadians, but they celebrate it in a different month, on a different day) and the Eid is one of the big food holidays for Muslims, and can you see where I am going with this? We have houseguests coming tomorrow and I was out of what are called here “digestive biscuits” (horrible name!) and what we call graham crackers, which make for a very quick and easy pie crust.

As the jello mix was cooling before I could add the walnuts and pineapple and celery, I thought I would zip to the grocery. It’s still early in the morning, after nine but before ten, I can get in and out before the crowds hit.

Wrong. Oh so very wrong. If it were a normal day, yes, in and out in a flash, but when two big holidays are about to collide, no, there are other early birds like me, all jockying for spaces, for carts, to get their veggies and fruits weighed, to get their purchases rung up . . .

Fortunately for me, the first wave, the real eager beavers, was slipping out with their packages, and I got a parking place. No worrying about getting a space near the entry – any space will do. Besides, the weather has cooled and walking a little extra is nice this time of year.

I also lucked out on the produce lines – while everyone lined up near the citrus fruits, no one seemed to notice there was another weigh station near the Indian veggies. Lucky me! (For my stateside friends, when you pick out your produce here, you have to have it weighed and labled with the price before you get to the check-out stand.)

All in all – it wasn’t to bad. Not in and out in a flash, but in and out not too bad. The cars were streaming in as I departed, and I vow not to return until the Eid is over!